In need of a Microsoft Postmaster

I am in great hopes that a Microsoft Postmaster could get in contact with me. This is dealing with a delisting of a banned IP "blocked using Blocklist 3, mail from IP banned" My client is e-mailing a vendor of theirs who's mail goes to "mail.messaging.microsoft.com" We have submitted a request to delist it but have not heard back from anyone for about 2 weeks now. Our client is up in arms and all that. There has been no know reasons for why the ban would have taken place. It is possible this is an old ban from before we had the IP space which we got 1-2 years ago. :( Sincerely, Mark Keymer CFO/COO Vivio Technologies